1. Field
The present disclosure relates to a composite, a catalyst including the composite, a fuel cell including the catalyst, and a lithium air battery including the catalyst.
2. Description of the Related Art
Fuel cells are power generating devices that directly convert the chemical energy of a fuel and an oxidant, such as hydrogen and oxygen, into electrical energy. Fuel cells can continuously generate electricity so long as a supply of fuel and an oxidant, such as hydrogen and oxygen, is provided, unlike a battery. Also, because fuel cells generate electricity directly, unlike other power generating devices, fuel cells can provided improved efficiency loss by avoiding multiple steps in the power generating process. The direct energy conversion provided by fuel cells may lead to efficiency twice as high as that of an internal combustion engine.
According to a type of an electrolyte and fuel used, fuel cells can be classified as polymer electrolyte membrane fuel cells (PEMFCs), direct methanol fuel cells (DMFCs), phosphoric acid fuel cells (PAFCs), molten carbonate fuel cells (MCFCs), and solid oxide fuel cells (SOFCs).
PEMFCs and DMFCs, which are power generating systems which electrochemically generate direct current (DC) electricity from hydrogen or methanol and oxygen, each include a membrane-electrode assembly (MEA). The MEA includes an anode to which a reaction liquid or gas is supplied, a cathode, and a proton conducting membrane disposed between the anode and the cathode.
In the anode protons are generated by oxidization of hydrogen or methanol by a catalyst. These protons pass through the proton conducting membrane and reach the cathode where the protons react with oxygen in the presence of a catalyst, thereby generating electricity. Thus, in fuel cells having such a structure as described above, the performance of the catalyst can determine the performance of the fuel cell.
A PEMFC MEA includes an amorphous carbon support with dispersed Pt particles on both in the anode and the cathode. A DMFC uses PtRu in the anode, and Pt in the cathode, which are used either in particulate form or dispersed on an amorphous carbon support.
Catalysts are a key contributing factor to the entire manufacturing cost of fuel cells, and may have a significant effect on mass production and commercialization of fuel cells. Therefore, there remains a need for improved catalysts that provide improved activity.